Endress+Hauser OxyMax W COS 41 User manual

Quality made by
Endress+Hauser
ISO 9001
BA 284C/07/en/05.01
No. 51506691 OxyMax W COS 41
Sensor for Measuring
Dissolved Oxygen
Operating Instructions

OxyMax W COS 41
Endress+Hauser
Contents
1 Safety instructions . . . . . . . . . . . . . . . . . 2
1.1 Notes on safety conventions and icons . . . . . . 2
1.2 Designated use . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Installation, comissioning and operation . . . . . 2
1.4 Operational safety . . . . . . . . . . . . . . . . . . . . . . 3
1.5 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Identification . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Product structure . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . 4
3 Installation . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Measuring device . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Installation conditions . . . . . . . . . . . . . . . . . . . 6
3.3 Installation location and position . . . . . . . . . . . 7
3.4 Sensor design and functional description . . . 11
3.5 Post-installation check . . . . . . . . . . . . . . . . . . 12
4 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1 Direct connection to the transmitter . . . . . . . . 13
4.2 Connection via the junction box VBM . . . . . . 13
4.3 Post-connection check . . . . . . . . . . . . . . . . . 14
5 Commissioning . . . . . . . . . . . . . . . . . . 15
5.1 Function check . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2 Polarisation . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6 Maintenance . . . . . . . . . . . . . . . . . . . . . . 18
6.1 Cleaning the outside of the sensor . . . . . . . . . 18
6.2 Regeneration . . . . . . . . . . . . . . . . . . . . . . . . . 19
7 Accessories . . . . . . . . . . . . . . . . . . . . . . . 22
7.1 Connection accessories . . . . . . . . . . . . . . . . . 22
7.2 Installation accessories . . . . . . . . . . . . . . . . . 22
7.3 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.4 Measurement, controlling and cleaning
the sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8 Trouble-shooting . . . . . . . . . . . . . . . . . 23
8.1 Trouble-shooting instructions . . . . . . . . . . . . . 23
8.2 Sensor test . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.3 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9 Technical data . . . . . . . . . . . . . . . . . . . . 25
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1 Safety instructions OxyMax W COS 41
2Endress+Hauser
1 Safety instructions
1.1 Notes on safety conventions and icons
#Warning!
This symbol alerts you to hazards which could cause serious injuries as well as
damage to the instrument if ignored.
"Caution!
This symbol alerts you to possible faults which could arise from incorrect operation.
They could cause damage to the instrument if ignored.
!Note!
This symbol indicates important items of information.
1.2 Designated use
The oxygen sensor COS 41 is suitable for continuous measurement of dissolved oxygen
in water.
Typical applications are:
•Measuring oxygen content in activated sludge basins.
The measuring signal is used for monitoring and as a control parameter.
•Checking oxygen content in the discharge of a sewage treatment plant.
•Monitoring public waters.
Measuring and controlling the oxygen content in fish farming water.
•Oxygen enrichment in drinking water.
#Warning!
•If the device is used for any application other than those described in this manual, it
may lead to unsafe and improper functioning of the measuring system and is therefore
not permitted.
•Make sure you strictly adhere to the warnings and notes in these Operating Instruc-
tions.
1.3 Installation, comissioning and operation
#Warning!
•Only trained technical personnel may carry out installation, electrical connection,
commissioning, operation and maintenance of the measuring system. The technical
personnel must be authorised to do this by the system operator.
•Technical personnel must be familiar with the instructions in this manual and must ad-
here to them.
•Before switching on the system, check all the connections again for correctness.
•Do not operate damaged sensors. Indicate them as being defective.
•Measuring point faults may only be remedied by authorised and trained personnel.
•If faults cannot be repaired, the sensor must be taken out of service and secured
against unintentional commissioning.
•Repairs may only be carried out by the manufacturer or by the Endress+Hauser serv-
ice organisation.

OxyMax W COS 41 1 Safety instructions
Endress+Hauser 3
1.4 Operational safety
The COS 41 sensor is operationally reliable and is made to the state of the art. The ap-
propriate regulations and EC directives (see "Technical data") have been met.
As the user, you are responsible for complying with the following safety conditions:
•Explosion protection regulations
•Installation instructions
•Operating instructions for the assembly and its materials
•Local prevailing standards and regulations
1.5 Return
If the device requires repair, please send the sensor clean (see page 18) to the appro-
priate Endress+Hauser sales offices. Please use the original packaging where possible.
Please add the filled in »Declaration of contamination« (copy the last but one page of
this manual) to the packing of the sensor and add it also to the shipping documents.
1.6 Disposal
Defective, non-repairable sensors must be disposed of.
Please keep to the local disposal regulations!

2 Identification OxyMax W COS 41
4Endress+Hauser
2 Identification
2.1 Product structure
COS 41
2.2 Scope of delivery
!Note!
•Make sure the packaging is undamaged!
Inform the post office or the courier of any damage to the packing.
Keep the damaged packaging until the matter has been clarified.
•Make sure the contents are undamaged!
Inform the post office or the courier of any damage to the delivered contents.
Keep the damaged products until the matter has been clarified.
•Use the delivery papers to check that the scope of delivery is complete.
The following items are included in the delivery:
•1 oxygen sensor COS 41 with transport protection cap for membrane protection
•1 Accessories Set COY 31-Z with the following contents:
–1 spare replacement cartridge COY 31-WP
–10 plastic ampoules containing electrolyte filling COY 3-F
–1 sealing kit COY 31-OR with 3 O-rings
–6 abrasive sheets
•Operating Instructions BA 284C/07/en
If you have questions, please contact your supplier or your nearest
Endress+Hauser sales office (see the back page of this Operating Instructions).
Cable length
2 Cable length 7 m
4 Cable length 15 m
8 without cable (only for TOP 68 version)
9 Special design to customer specifications
Cable connection
F Fixed cable connection
S Cable connection using TOP 68 plug
COS 41- Complete order code

OxyMax W COS 41 3 Installation
Endress+Hauser 5
3Installation
3.1 Measuring device
A complete measuring system comprises:
•Oxygen sensor COS 41
•Oxygen transmitter Liquisys M COM 223/253-DX/DS
Optional:
•Universal suspension assembly support CYH 101 for immersed operation
•Immersion assembly COA 110 or DipFit W CYA 611 or flow assembly FlowFit W COA
250 or retractable assembly Probfit W COA 461
•Junction box VBM
•Automatic spray cleaning system Chemoclean
Fig. 3.1: Complete measuring device for COS 41 with Liquisys M COM 223/253-DX/DS
1 VBM junction box (only if cable extension required)
2 Transmitter Liquisys M COM 223/253-DX/DS
3 Immersion assembly CYA 611
4 Oxygen sensor COS 41
C07-COS4xxxx-14-05-00-xx-001.EPS
12
3
4

3 Installation OxyMax W COS 41
6Endress+Hauser
3.2 Installation conditions
3.2.1 Installation dimensions
Fig. 3.2: Dimensions COS 41
fixed cable version Fig. 3.3: COS 41 with TOP 68 plug-in head and TOP 68 plug-in cable
171
Ø40
144
190
C07-COS41xxx-06-05-00-xx-001.EPS
C07-COS41xxx-06-05-00-xx-002.EPS

OxyMax W COS 41 3 Installation
Endress+Hauser 7
3.3 Installation location and position
The sensor can be installed up to the horizontal in an assembly, support or a suitable
process connection (Fig. 3.4). Other angles are not permissible. Do not install the sen-
sor overhead.
Permissible installation .
Fig. 3.4: Permissible installation positions for the COS 41 oxygen sensor
!Note!
Make sure you comply with the instructions for installing sensors. You will find them in
the Operating Instructions for the assembly used.
Installing a
measuring point
For a complete installation of a measuring point, proceed as follows:
1. Installing an retractable or an flow assembly (if used) into the process.
2. Water connection to the rinse connections (if you use an assembly with cleaning
function).
3. Installing and connecting the oxygen sensor.
4. Installing an immersion or an suspension assembly (if used) into the process.
"Caution!
•For immersed operation, the sensor must be installed in an immersion assembly (e.g.
CYA 611). Do not install the sensor suspended from the cable.
•Screw the sensor into the assembly so that the cable is not twisted.
•Avoid exerting excessive tensile force on the cable (e.g. from jerky pulling).
•Select the installation location so that there is easy access for later calibration.
#Warning!
When using metallic assemblies and installation equipment, comply with national
grounding regulations.
Pre-installation
For immersed operation, install the individual modules away from the basin on a solid
base. Only carry out the final installation at the intended installation location.
Placing
Select the installation location so that there is easy access for later calibration. Make
sure that upright posts and assemblies are secured safely and vibration-free. For
immersed operation in an activated sludge basin, select an installation location which
produces a typical oxygen concentration.
C07-COS41xxx-11-05-00-en-001.EPS
Permissible angle of installation

3 Installation OxyMax W COS 41
8Endress+Hauser
3.3.1 Installation examples
Immersed operation
For large basins, where sufficient installation distance is required from the basin edge,
it is advisable to use the upright post and chain assembly (Figs. 3.5 and 3.6). The
free swinging of the immersed assembly practically rules out vibrations from the upright
post.
Fig. 3.5: Universal assembly support CYH 101-A with immersible
pendulum assembly CYA 611 Fig. 3.6: CYA 611: Components and dimensions
1
2
3
4
5
6
7
8
9
10
Weather protection cover
Dummy plug
Upright post square pipe stainless steel AISI 304
Transverse pipe stainless steel AISI 304
Velco fastener
Plastic chain, length 5 m
Immersion assembly CYA 611
Second fixing possibility for transverse pipe
Plastic shackle
Star handle
1
2
3
4
5
Protective cap
Worm drive hose clip
Pipe clips (detailed drawing in right half of figure)
PVC pipe
Threaded coupling
C07-COS41xxx-11-05-00-xx-002.EPS
60 x 60 x 2
max. 1400
1480 Ø36 x 1,6
1500
950
450
4 x Ø12 60 x 60 x 2
120
1
2
3
45
6
7
10
9
8
C07-COS41xxx-11-05-00-004.EPS
1
2
3
4
5
625
58
Ø6,5
Ø14
Ø40
22
60
1580
1630
Ø48
Ø40

OxyMax W COS 41 3 Installation
Endress+Hauser 9
The preferable type of installation for strong or turbulent flow (> 0.5 m/s) in the basin or
open channels is to secure the device to an upright post and a securely mounted im-
mersion tube (Fig. 3.7). If the flow is very strong, a second transverse pipe (10) can be
installed with its own pipe support.
For simple fixing to the sides of the basin or channel, we recommend the use of an
immersion tube basin edge mounting (see Fig.).
If there is strong turbulence or flow, a second basin edge mounting must be used for an
immersion tube.
Fig. 3.7: Universal assembly support CYH 101-D or E
1
2
3
4
5
6
7
8
9
10
Weather protection cover
Dummy plug
Upright post square pipe stainless steel AISI 304
Transverse pipe stainless steel AISI 304
Star handle
Velco fastener
Immersion tube
Pipe holder
Fixing bracket
Second fixing possibility for transverse pipe
Fig. 3.8: Horizontal basin edge mounting CYY
106-A with immersion tube CYY 105-A Fig. 3.9: Vertical basin edge mounting CYY 106- A with immersion tube CYY 105-A
1
2
3
Shrouding cover for cable entry
Pipe holder
Immersion tube SS 304
4
5Basin edge mounting Star handle
C07-COS41xxx-11-05-00-xx-003.EPS
+
1
2
3
45
6
58
9
7
7
10
5
1
2
3
4
5
C07-COS41xxx-11-05-00-xx-005.EPS
C07-COS41xxx-11-05-00-xx-006.EPS
1
2
3
5
4

3 Installation OxyMax W COS 41
10 Endress+Hauser
To aid installation in strongly fluctuating water levels, e.g. in rivers or lakes, there is a
floating body COA 110-50 available (Fig. 3.10).
Flow operation
The COA 250-A flow assembly (Fig. 3.11) with automatic self-venting is suitable for use
in pipelines or hose connections. The inlet is at the bottom of the assembly, the outlet at
the top (connection thread G ¾). It can be installed in a pipe by using two 90°pipe
brackets to allow inflow to the assembly (Fig. 3.12, Pos. 6).
1
2
3
4
5
6
7
Cable route with strain relief and rain
protection
Mounting ring for ropes and chains
with locking screw
Lugs Ø 15; 3x120° for anchoring
Saltwater-resistant plastic float
Pipe 40x1, rust-proof steel SS 316Ti
Shock absorber and weight
Oxygen sensor COS 41
Fig. 3.10: Float COA 110-50
Fig. 3.11: Flow assembly COA 250-A Fig. 3.12: Bypass installation with manually
actuated valves or solenoid valves
1 Screw-in part for sensor 1 Main line
2 Screw ring 2 Medium return
3 Meter body 3 COS 41
4 Connection thread G ¾ 4, 7 Manually actuated or solenoid valves
5 Dummy plug on the connection 5 Flow assembly COA 250-A
thread for spray head COR 3 6 90° pipe bracket
8 Medium removal
800
500 220
Ø200
1
2
3
4
5
6
7
G1
C07-COS41xxx-11-05-00-xx-007.EPS
7
-COS41xxx-11-05-00-xx-008.EPS
100
90
Ø34
23
90
G ¾
68
196
G¾
Ø34
1
2
3
4
1
23
4
6
7
8
C07-COS41xxx-11-05-00-xx-009.EPS
5

OxyMax W COS 41 3 Installation
Endress+Hauser 11
"Caution!
For pressures > atmospheric pressure
•Pressurisation and work at a constant overpressure up to 10 bar poses no problems.
•Rapid pressure loss at the measuring point leads to air degassing in the electrolyte
due to the sudden reductions in solubility. This could lead to a swelling of the sensor
membrane.
Avoid this problem by keeping up the pressure on the sensor. In the case of rapid
pressure loss e.g. during maintenance work on the pipeline close all the valves
(manual mode: manually actuated valves, automatic mode: solenoid valves, see Fig.
3.12, Pos. 4 and 7) of the assembly.
3.4 Sensor design and functional description
The figure on the next page shows an enlarged side view (Fig. 3.14) and top view
(Fig. 3.15) of the sensor head.
3.4.1 Design
The sensor consists of the following
function units:
•Sensor body
•sensor head with gold cathode and
anode
•Membrane cap with electrolyte filling
•Protection basket
The electrical connection is either done by
a fixed cable (1) or by a TOP 68 plug-in
connection.
The threaded connections NPT ¾’’ (2) and
G 1 (3) are designed for installing the
sensor in an immersion or flow assembly.
The protection basket (5) is screwed on.
Alternatively to the protection basket, you
can use a spray head COR 3 (optional,
see "Accessories", page 22) for use in
immersed operation with cleaning func-
tion.
The membrane cap screwed onto the sen-
sor head is filled with electrolyte. The
screw connection seals it from the
medium.
The membrane which is in contact with the
medium is seated tightly in the membrane
cap (pretensioned in the factory).
The gold cathode (6), anode (Ag/AgBr, 9)
and an internal temperature sensor are
located inside the sensor head.
Fig. 3.13: Sensor design COS 41
1 Sensor cable
2 Threaded connection NPT ¾
3 Threaded connection G 1
4 Sensor body
5 Protection basket
6 Gold cathode
7 Membrane
8 Electrolyte
9 Anode
1
3
4
5
6
7
8
9
2
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3 Installation OxyMax W COS 41
12 Endress+Hauser
3.4.2 Functional description
Polarisation
When the sensor is connected to the transmitter, a fixed external voltage is applied
between the cathode and anode. The resulting polarisation current is indicated on a dis-
play on the transmitter. The current starts high but then drops over time. The sensor can
only be calibrated when the display is stable.
Membrane
The oxygen dissolved in the medium is conveyed to the membrane by the incoming
flow. The membrane is only permeable for dissolved gases. Other substances dis-
solved in the liquid phase e.g. ionic substances, will not penetrate through the mem-
brane. Therefore, medium conductivity has no impact on the measuring signal.
Amperometric measuring principle
The oxygen molecules diffused through the membrane are reduced to hydroxide ions
(OH-) at the gold cathode. Silver is oxidised to silver ions (Ag+) at the anode (this forms
a silver bromide layer, AgBr).
A current flows due to the connected electrode release at the gold cathode and
accepted at the anode. In equilibrium, this flow is proportional to the oxygen content of
the medium.
This current is converted in the measuring instrument and indicated on the display
as an oxygen concentration in mg/l, as a saturation index in % SAT or as an oxygen
partial pressure in hPa.
3.5 Post-installation check
After installing the sensor, carry out the following checks:
Fig. 3.14: Sensor head with membrane cap
(Side view with cut-away view of
membrane cap)
Fig. 3.15: Sensor head (top view with membrane
cap removed)
1 Screw thread for protection basket 5 Membrane
2 Sealing ring 6 Membrane cap
3 Screw thread for membrane cap 7 Anode
4 Electrolyte 8 Gold cathode
Checks Remarks
Membrane OK (visual inspection)? Replace membrane if there is a leak.
Compliance with permissible sensor installation position? see Chapter 3.3
Sensor installed in immersion assembly? Do not install the sensor suspended from the cable.
Protective cap fitted to immersion assembly? Avoid moisture by rain in the assembly.
C07-COS41xxx-16-05-07-xx-001.EPS
1
2
3
4
5
6
7
C07-COS41xxx-16-05-03-xx-002.EPS
8

OxyMax W COS 41 4 Wiring
Endress+Hauser 13
4Wiring
4.1 Direct connection to the transmitter
The sensor COS 41 is connected using a special measuring cable. The wiring diagram
is contained in the Operating Instructions of the transmitter Liquisys M COM 223/253-
DX/DS
4.2 Connection via the junction box VBM
To lengthen the sensor connection beyond the length of the fixed cable, you require a
junction box VBM. The connection is lengthened to the transmitter using the special
measuring cable CYK 71.
Figs. 4.1 and 4.2 show the junction box VBM with its dimensions. The special measuring
cable CYK 71 is depicted in Fig. 4.3. Please refer to it for information on the terminals
and their assignment for connection to the transmitter. The interior white and yellow pilot
wires have no function.
Special measuring cable
CYK 71
Fig. 4.4 on page 14 is a schematic diagram of the sensor connection to the junction box
VBM.
Fig. 4.1: Junction box VBM, side view Fig. 4.2: Junction box VBM, plan view
54
26,8
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136
52
80
Pg 13,5
113
125
62,5
10
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Terminal Assignment
S Outer screening
12 Active inner screening
(NTC temperature sensor)
90 Cathode
91 Anode
11 NTC temperature sensor
Fig. 4.3: Special measuring cable CYK 71
BR
GN
WH
RD
C07-COS41xxx-04-05-00-de-001.EPS

4Wiring OxyMax W COS 41
14 Endress+Hauser
Connection diagram with
junction box
4.3 Post-connection check
After wiring up the electrical connection, carry out the following checks:
COS 41 Sensor
connecting
cable
Junction box
VBM
Special
measuring
cable
CYK 71
Transmitter
Liquisys M COM 223/253-DX/DS
Fig. 4.4: Connection diagram with junction box VBM
Instrument status and specifications Remarks
Are the sensor, assembly, junction box or cable damaged ? Visual inspection
Electrical connection Remarks
Does the supply voltage of the transmitter match the specifications on the
nameplate ?
100 V ... 230 V AC long-range
24 V AC / DC
Are the installed cables strain-relieved and not twisted ?
Is the cable type route completely isolated ? Power cable/weak current cable
Are the power supply and signal cable correctly connected to the
transmitter ?
Are all the screws terminals properly tightened ? Use the connection diagram of
COM 2x3.
Are all the cable entries installed, tightened and sealed ?
Are all the cable entries installed downwards or lateral ?
For cable entries lateral: cable loops downwards for water to be able to
drip off.
C07-COS41xxx-04-05-00-xx-002.EPS
A
K
NTC
BR BR
RD
GN GN

OxyMax W COS 41 5 Commissioning
Endress+Hauser 15
5 Commissioning
5.1 Function check
Before the first commissioning, make sure of the following points:
•That the sensor was correctly installed (Post-installation check, see Chapter 3.5)
•That the electrical connection is correct (Post-connection check, see Chapter 4.3)
If using an assembly with automatic cleaning, check the correct water connection at the
assembly rinse connection.
#Warning!
Danger of medium escaping.
Before applying compressed air to an assembly with cleaning facility, make sure the
connections are correctly fitted. Otherwise, the assembly may not be insert into the
process.
5.2 Polarisation
The sensor was tested in the factory for perfect functionality and is supplied ready for
operation.
To prepare for calibration, proceed as follows:
•Remove the sensor protective cap.
•Place the externally dry sensor in atmospheric air.
The air should be saturated with water vapour. Therefore, install the sensor as close
to the water surface as possible. When calibrating the sensor membrane, make sure
the membrane remains dry.
Therefore, avoid any direct contact with the water surface.
•Connect the sensor to the transmitter and switch on the transmitter.
•If you connect the sensor to the transmitter Liquisys M COM 223/253-DX/DS,
polarisation is automatically performed after switching on the transmitter.
•The polarisation time takes about 1 hour.
Polarisation starts high, then drops gradually. You will recognise the end of polarisation
when the display stabilises and remains practically constant.
"Caution!
When you remove the sensor from the medium, protect the sensor from strong sunlight.
Make sure you comply with the instructions for commissioning and calibration in the Op-
erating Instructions of the transmitter.

5 Commissioning OxyMax W COS 41
16 Endress+Hauser
5.3 Calibration
Calibration is a means of adapting the transmitter to the characteristic values of the sen-
sor. As no zero calibration is required for the sensor COS 41, a single-point calibration
is carried out in the presence of oxygen.
There are three basic types of calibration:
•In air (preferably saturated water vapour, e.g. near the water surface)
•In air-saturated water
•By entering a reference measured value in the transmitter
(sensor remains in the medium).
Following only the calibration in air is discribed because it is the easiest and that’s why
the recommended method of calibration.
Calibration in air is only possible if air temperature ≥ –5 °C.
The sensor requires calibration after:
•first commissioning
•replacing a membrane or electrolyte
•cleaning the gold cathode
•long breaks in operation without power supply
•typical time intervals dependent on operating experience
5.3.1 Calibration in air
To calibrate the sensor in air, proceed as follows:
•Remove the sensor from the medium.
•Clean the outside of the sensor with a damp cloth. Then dry the sensor membrane e.g.
by using a tissue.
•If the sensor is removed from a closed pressure system with a process pressure great-
er than atmospheric pressure:
–open the membrane cap to equilibrate the pressure and clean the cap if necessary.
–Change the electrolyte filling and close the membrane cap again.
–Wait for the polarisation time to end.
•Then wait while the sensor adjusts to the temperature of the ambient air. This takes
about 20 minutes. Check that the sensor is not in direct sunlight during this time.
•If the measured value display on the transmitter is stable, carry out the calibration in
accordance with the Operating Instructions of the transmitter.
•Place the sensor in the medium again.
!Note!
Make sure you comply with the instructions for calibration in the Operating Instructions
of the transmitter.
5.3.2 Calculation example for the calibration value
As a check, you can calculate the expected calibration value (transmitter display) as
shown in the following example.
Salinity is 0.
1. Determine:
•The sensor temperature (ambient air)
•The altitude above sea level.
•The current air pressure (rel. air pressure to sea level) at the time of calibration.
(If undeterminable, use 1013 hPa for an approximate calculation.)
2. Define:
•The saturation value Sacc. to Table 1 on page 17
•The factor Kacc. to Table 2 on page 17

OxyMax W COS 41 5 Commissioning
Endress+Hauser 17
3. Determine:
•L = [rel. air pressure at calibration] : [1013 hPa]
•M=1.02 for calibration in air
M=1.00 for calibration in air-saturated water
4. Calculate the calibration value:
Calibration value = S • K • L • M
Example:
•Air calibration at 18°C, altitude 500 m above sea level, air pressure 1022 hPa
•S = 9.45 mg/l, K = 0.943, L = 1.0089, M = 1.02
Calibration value = 9.17 mg/l
Table 1:
Saturation value S as a factor of temperature
(taken at an air pressure of 1013 hPa)
Table 2:
Correction factor K as a factor of mean altitude
(above sea level)
°CS [mg/l] °CS [mg/l] °CS [mg/l] °CS [mg/l]
0 14.64 11 10.99 21 8.90 31 7.42
1 14.23 12 10.75 22 8.73 32 7.30
2 13.83 13 10.51 23 8.57 33 7.18
3 13.45 14 10.28 24 8.41 34 7.06
4 13.09 15 10.06 25 8.25 35 6.94
5 12.75 16 9.85 26 8.11 36 6.83
6 12.42 17 9.64 27 7.96 37 6.72
7 12.11 18 9.45 28 7.82 38 6.61
8 11.81 19 9.26 29 7.69 39 6.51
9 11.53 20 9.08 30 7.55 40 6.41
10 11.25
Altitude
[m] KAltitude [m] KAltitude [m] KAltitude [m] K
0 1.000 550 0.938 1050 0.885 1550 0.834
50 0.994 600 0.932 1100 0.879 1600 0.830
100 0.988 650 0.927 1150 0.874 1650 0.825
150 0.982 700 0.922 1200 0.869 1700 0.820
200 0.977 750 0.916 1250 0.864 1750 0.815
250 0.971 800 0.911 1300 0.859 1800 0.810
300 0.966 850 0.905 1350 0.854 1850 0.805
350 0.960 900 0.900 1400 0.849 1900 0.801
400 0.954 950 0.895 1450 0.844 1950 0.796
450 0.949 1000 0.890 1500 0.839 2000 0.792
500

6 Maintenance OxyMax W COS 41
18 Endress+Hauser
6 Maintenance
Maintenance work must carried out at regular intervals. To ensure that it is carried out,
we recommend you enter the maintenance dates into an operations logbook or in an
operations calendar in advance.
The following activities must be carried out:
•Cleaning the sensor
In particular when the membrane is soiled (see Chapter 6.1).
•Check the measuring function
A simple inspection of the measuring function is to remove the sensor from the
medium. Clean and dry the membrane. After about 10 minutes, measure the oxygen
saturation index in air (without recalibration). The measured value should be near to
102% SAT (display of O2saturation with COM 2x3 by pressing 4 times »+«- key).
•Replace a defective membrane or one which cannot be cleaned any more.
•Recalibration (see Chapter 5.3.1)
!Note!
For regular automatic sensor cleaning, we recommend equipping
the measuring point with a fully-automatic cleaning system,
e. g. Chemoclean (see "Accessories" on page 22).
6.1 Cleaning the outside of the sensor
The measurement can be corrupted by sensor fouling or malfunction, e.g.:
•Coatings on the sensor membrane
→cause longer response times and a reduced slope.
•Soiling or poisoning of the electrolyte
→causes longer response times and false measurement.
To ensure reliable measurement, the sensor must be cleaned at regular intervals. The
frequency and intensity of the cleaning operation depend on the measuring medium.
Clean the sensor:
•before every calibration
•at regular intervals during operation as necessary.
•before returning it to Endress+Hauser for repairs.
Depending on the type of soiling, proceed as follows:
"Caution!
After cleaning, rinse the sensor with copious amounts of clean water.
Type of soiling Cleaning measure
Salt deposits Immerse the sensor in drinking water or in 1-5% hydrochloric acid
for a few minutes. Afterwards, rinse it with copious amounts of water.
Dirt particles on the sensor body
(not the membrane) Clean the sensor body mechanically with water and a suitable brush.
Dirt particles on the membrane cap or
the membrane
Clean the membrane with water and a soft sponge.